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keyctl.c
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// SPDX-License-Identifier: GPL-2.0-or-later
/* Userspace key control operations
*
* Copyright (C) 2004-5 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*/
#include <linux/init.h>
#include <linux/sched.h>
#include <linux/sched/task.h>
#include <linux/slab.h>
#include <linux/syscalls.h>
#include <linux/key.h>
#include <linux/keyctl.h>
#include <linux/fs.h>
#include <linux/capability.h>
#include <linux/cred.h>
#include <linux/string.h>
#include <linux/err.h>
#include <linux/vmalloc.h>
#include <linux/security.h>
#include <linux/uio.h>
#include <linux/uaccess.h>
#include <keys/request_key_auth-type.h>
#include "internal.h"
#define KEY_MAX_DESC_SIZE 4096
static const unsigned char keyrings_capabilities[2] = {
[0] = (KEYCTL_CAPS0_CAPABILITIES |
(IS_ENABLED(CONFIG_PERSISTENT_KEYRINGS) ? KEYCTL_CAPS0_PERSISTENT_KEYRINGS : 0) |
(IS_ENABLED(CONFIG_KEY_DH_OPERATIONS) ? KEYCTL_CAPS0_DIFFIE_HELLMAN : 0) |
(IS_ENABLED(CONFIG_ASYMMETRIC_KEY_TYPE) ? KEYCTL_CAPS0_PUBLIC_KEY : 0) |
(IS_ENABLED(CONFIG_BIG_KEYS) ? KEYCTL_CAPS0_BIG_KEY : 0) |
KEYCTL_CAPS0_INVALIDATE |
KEYCTL_CAPS0_RESTRICT_KEYRING |
KEYCTL_CAPS0_MOVE
),
[1] = (KEYCTL_CAPS1_NS_KEYRING_NAME |
KEYCTL_CAPS1_NS_KEY_TAG |
(IS_ENABLED(CONFIG_KEY_NOTIFICATIONS) ? KEYCTL_CAPS1_NOTIFICATIONS : 0)
),
};
static int key_get_type_from_user(char *type,
const char __user *_type,
unsigned len)
{
int ret;
ret = strncpy_from_user(type, _type, len);
if (ret < 0)
return ret;
if (ret == 0 || ret >= len)
return -EINVAL;
if (type[0] == '.')
return -EPERM;
type[len - 1] = '\0';
return 0;
}
/*
* Extract the description of a new key from userspace and either add it as a
* new key to the specified keyring or update a matching key in that keyring.
*
* If the description is NULL or an empty string, the key type is asked to
* generate one from the payload.
*
* The keyring must be writable so that we can attach the key to it.
*
* If successful, the new key's serial number is returned, otherwise an error
* code is returned.
*/
SYSCALL_DEFINE5(add_key, const char __user *, _type,
const char __user *, _description,
const void __user *, _payload,
size_t, plen,
key_serial_t, ringid)
{
key_ref_t keyring_ref, key_ref;
char type[32], *description;
void *payload;
long ret;
ret = -EINVAL;
if (plen > 1024 * 1024 - 1)
goto error;
/* draw all the data into kernel space */
ret = key_get_type_from_user(type, _type, sizeof(type));
if (ret < 0)
goto error;
description = NULL;
if (_description) {
description = strndup_user(_description, KEY_MAX_DESC_SIZE);
if (IS_ERR(description)) {
ret = PTR_ERR(description);
goto error;
}
if (!*description) {
kfree(description);
description = NULL;
} else if ((description[0] == '.') &&
(strncmp(type, "keyring", 7) == 0)) {
ret = -EPERM;
goto error2;
}
}
/* pull the payload in if one was supplied */
payload = NULL;
if (plen) {
ret = -ENOMEM;
payload = kvmalloc(plen, GFP_KERNEL);
if (!payload)
goto error2;
ret = -EFAULT;
if (copy_from_user(payload, _payload, plen) != 0)
goto error3;
}
/* find the target keyring (which must be writable) */
keyring_ref = lookup_user_key(ringid, KEY_LOOKUP_CREATE, KEY_NEED_WRITE);
if (IS_ERR(keyring_ref)) {
ret = PTR_ERR(keyring_ref);
goto error3;
}
/* create or update the requested key and add it to the target
* keyring */
key_ref = key_create_or_update(keyring_ref, type, description,
payload, plen, KEY_PERM_UNDEF,
KEY_ALLOC_IN_QUOTA);
if (!IS_ERR(key_ref)) {
ret = key_ref_to_ptr(key_ref)->serial;
key_ref_put(key_ref);
}
else {
ret = PTR_ERR(key_ref);
}
key_ref_put(keyring_ref);
error3:
kvfree_sensitive(payload, plen);
error2:
kfree(description);
error:
return ret;
}
/*
* Search the process keyrings and keyring trees linked from those for a
* matching key. Keyrings must have appropriate Search permission to be
* searched.
*
* If a key is found, it will be attached to the destination keyring if there's
* one specified and the serial number of the key will be returned.
*
* If no key is found, /sbin/request-key will be invoked if _callout_info is
* non-NULL in an attempt to create a key. The _callout_info string will be
* passed to /sbin/request-key to aid with completing the request. If the
* _callout_info string is "" then it will be changed to "-".
*/
SYSCALL_DEFINE4(request_key, const char __user *, _type,
const char __user *, _description,
const char __user *, _callout_info,
key_serial_t, destringid)
{
struct key_type *ktype;
struct key *key;
key_ref_t dest_ref;
size_t callout_len;
char type[32], *description, *callout_info;
long ret;
/* pull the type into kernel space */
ret = key_get_type_from_user(type, _type, sizeof(type));
if (ret < 0)
goto error;
/* pull the description into kernel space */
description = strndup_user(_description, KEY_MAX_DESC_SIZE);
if (IS_ERR(description)) {
ret = PTR_ERR(description);
goto error;
}
/* pull the callout info into kernel space */
callout_info = NULL;
callout_len = 0;
if (_callout_info) {
callout_info = strndup_user(_callout_info, PAGE_SIZE);
if (IS_ERR(callout_info)) {
ret = PTR_ERR(callout_info);
goto error2;
}
callout_len = strlen(callout_info);
}
/* get the destination keyring if specified */
dest_ref = NULL;
if (destringid) {
dest_ref = lookup_user_key(destringid, KEY_LOOKUP_CREATE,
KEY_NEED_WRITE);
if (IS_ERR(dest_ref)) {
ret = PTR_ERR(dest_ref);
goto error3;
}
}
/* find the key type */
ktype = key_type_lookup(type);
if (IS_ERR(ktype)) {
ret = PTR_ERR(ktype);
goto error4;
}
/* do the search */
key = request_key_and_link(ktype, description, NULL, callout_info,
callout_len, NULL, key_ref_to_ptr(dest_ref),
KEY_ALLOC_IN_QUOTA);
if (IS_ERR(key)) {
ret = PTR_ERR(key);
goto error5;
}
/* wait for the key to finish being constructed */
ret = wait_for_key_construction(key, 1);
if (ret < 0)
goto error6;
ret = key->serial;
error6:
key_put(key);
error5:
key_type_put(ktype);
error4:
key_ref_put(dest_ref);
error3:
kfree(callout_info);
error2:
kfree(description);
error:
return ret;
}
/*
* Get the ID of the specified process keyring.
*
* The requested keyring must have search permission to be found.
*
* If successful, the ID of the requested keyring will be returned.
*/
long keyctl_get_keyring_ID(key_serial_t id, int create)
{
key_ref_t key_ref;
unsigned long lflags;
long ret;
lflags = create ? KEY_LOOKUP_CREATE : 0;
key_ref = lookup_user_key(id, lflags, KEY_NEED_SEARCH);
if (IS_ERR(key_ref)) {
ret = PTR_ERR(key_ref);
goto error;
}
ret = key_ref_to_ptr(key_ref)->serial;
key_ref_put(key_ref);
error:
return ret;
}
/*
* Join a (named) session keyring.
*
* Create and join an anonymous session keyring or join a named session
* keyring, creating it if necessary. A named session keyring must have Search
* permission for it to be joined. Session keyrings without this permit will
* be skipped over. It is not permitted for userspace to create or join
* keyrings whose name begin with a dot.
*
* If successful, the ID of the joined session keyring will be returned.
*/
long keyctl_join_session_keyring(const char __user *_name)
{
char *name;
long ret;
/* fetch the name from userspace */
name = NULL;
if (_name) {
name = strndup_user(_name, KEY_MAX_DESC_SIZE);
if (IS_ERR(name)) {
ret = PTR_ERR(name);
goto error;
}
ret = -EPERM;
if (name[0] == '.')
goto error_name;
}
/* join the session */
ret = join_session_keyring(name);
error_name:
kfree(name);
error:
return ret;
}
/*
* Update a key's data payload from the given data.
*
* The key must grant the caller Write permission and the key type must support
* updating for this to work. A negative key can be positively instantiated
* with this call.
*
* If successful, 0 will be returned. If the key type does not support
* updating, then -EOPNOTSUPP will be returned.
*/
long keyctl_update_key(key_serial_t id,
const void __user *_payload,
size_t plen)
{
key_ref_t key_ref;
void *payload;
long ret;
ret = -EINVAL;
if (plen > PAGE_SIZE)
goto error;
/* pull the payload in if one was supplied */
payload = NULL;
if (plen) {
ret = -ENOMEM;
payload = kvmalloc(plen, GFP_KERNEL);
if (!payload)
goto error;
ret = -EFAULT;
if (copy_from_user(payload, _payload, plen) != 0)
goto error2;
}
/* find the target key (which must be writable) */
key_ref = lookup_user_key(id, 0, KEY_NEED_WRITE);
if (IS_ERR(key_ref)) {
ret = PTR_ERR(key_ref);
goto error2;
}
/* update the key */
ret = key_update(key_ref, payload, plen);
key_ref_put(key_ref);
error2:
kvfree_sensitive(payload, plen);
error:
return ret;
}
/*
* Revoke a key.
*
* The key must be grant the caller Write or Setattr permission for this to
* work. The key type should give up its quota claim when revoked. The key
* and any links to the key will be automatically garbage collected after a
* certain amount of time (/proc/sys/kernel/keys/gc_delay).
*
* Keys with KEY_FLAG_KEEP set should not be revoked.
*
* If successful, 0 is returned.
*/
long keyctl_revoke_key(key_serial_t id)
{
key_ref_t key_ref;
struct key *key;
long ret;
key_ref = lookup_user_key(id, 0, KEY_NEED_WRITE);
if (IS_ERR(key_ref)) {
ret = PTR_ERR(key_ref);
if (ret != -EACCES)
goto error;
key_ref = lookup_user_key(id, 0, KEY_NEED_SETATTR);
if (IS_ERR(key_ref)) {
ret = PTR_ERR(key_ref);
goto error;
}
}
key = key_ref_to_ptr(key_ref);
ret = 0;
if (test_bit(KEY_FLAG_KEEP, &key->flags))
ret = -EPERM;
else
key_revoke(key);
key_ref_put(key_ref);
error:
return ret;
}
/*
* Invalidate a key.
*
* The key must be grant the caller Invalidate permission for this to work.
* The key and any links to the key will be automatically garbage collected
* immediately.
*
* Keys with KEY_FLAG_KEEP set should not be invalidated.
*
* If successful, 0 is returned.
*/
long keyctl_invalidate_key(key_serial_t id)
{
key_ref_t key_ref;
struct key *key;
long ret;
kenter("%d", id);
key_ref = lookup_user_key(id, 0, KEY_NEED_SEARCH);
if (IS_ERR(key_ref)) {
ret = PTR_ERR(key_ref);
/* Root is permitted to invalidate certain special keys */
if (capable(CAP_SYS_ADMIN)) {
key_ref = lookup_user_key(id, 0, KEY_SYSADMIN_OVERRIDE);
if (IS_ERR(key_ref))
goto error;
if (test_bit(KEY_FLAG_ROOT_CAN_INVAL,
&key_ref_to_ptr(key_ref)->flags))
goto invalidate;
goto error_put;
}
goto error;
}
invalidate:
key = key_ref_to_ptr(key_ref);
ret = 0;
if (test_bit(KEY_FLAG_KEEP, &key->flags))
ret = -EPERM;
else
key_invalidate(key);
error_put:
key_ref_put(key_ref);
error:
kleave(" = %ld", ret);
return ret;
}
/*
* Clear the specified keyring, creating an empty process keyring if one of the
* special keyring IDs is used.
*
* The keyring must grant the caller Write permission and not have
* KEY_FLAG_KEEP set for this to work. If successful, 0 will be returned.
*/
long keyctl_keyring_clear(key_serial_t ringid)
{
key_ref_t keyring_ref;
struct key *keyring;
long ret;
keyring_ref = lookup_user_key(ringid, KEY_LOOKUP_CREATE, KEY_NEED_WRITE);
if (IS_ERR(keyring_ref)) {
ret = PTR_ERR(keyring_ref);
/* Root is permitted to invalidate certain special keyrings */
if (capable(CAP_SYS_ADMIN)) {
keyring_ref = lookup_user_key(ringid, 0,
KEY_SYSADMIN_OVERRIDE);
if (IS_ERR(keyring_ref))
goto error;
if (test_bit(KEY_FLAG_ROOT_CAN_CLEAR,
&key_ref_to_ptr(keyring_ref)->flags))
goto clear;
goto error_put;
}
goto error;
}
clear:
keyring = key_ref_to_ptr(keyring_ref);
if (test_bit(KEY_FLAG_KEEP, &keyring->flags))
ret = -EPERM;
else
ret = keyring_clear(keyring);
error_put:
key_ref_put(keyring_ref);
error:
return ret;
}
/*
* Create a link from a keyring to a key if there's no matching key in the
* keyring, otherwise replace the link to the matching key with a link to the
* new key.
*
* The key must grant the caller Link permission and the keyring must grant
* the caller Write permission. Furthermore, if an additional link is created,
* the keyring's quota will be extended.
*
* If successful, 0 will be returned.
*/
long keyctl_keyring_link(key_serial_t id, key_serial_t ringid)
{
key_ref_t keyring_ref, key_ref;
long ret;
keyring_ref = lookup_user_key(ringid, KEY_LOOKUP_CREATE, KEY_NEED_WRITE);
if (IS_ERR(keyring_ref)) {
ret = PTR_ERR(keyring_ref);
goto error;
}
key_ref = lookup_user_key(id, KEY_LOOKUP_CREATE, KEY_NEED_LINK);
if (IS_ERR(key_ref)) {
ret = PTR_ERR(key_ref);
goto error2;
}
ret = key_link(key_ref_to_ptr(keyring_ref), key_ref_to_ptr(key_ref));
key_ref_put(key_ref);
error2:
key_ref_put(keyring_ref);
error:
return ret;
}
/*
* Unlink a key from a keyring.
*
* The keyring must grant the caller Write permission for this to work; the key
* itself need not grant the caller anything. If the last link to a key is
* removed then that key will be scheduled for destruction.
*
* Keys or keyrings with KEY_FLAG_KEEP set should not be unlinked.
*
* If successful, 0 will be returned.
*/
long keyctl_keyring_unlink(key_serial_t id, key_serial_t ringid)
{
key_ref_t keyring_ref, key_ref;
struct key *keyring, *key;
long ret;
keyring_ref = lookup_user_key(ringid, 0, KEY_NEED_WRITE);
if (IS_ERR(keyring_ref)) {
ret = PTR_ERR(keyring_ref);
goto error;
}
key_ref = lookup_user_key(id, KEY_LOOKUP_PARTIAL, KEY_NEED_UNLINK);
if (IS_ERR(key_ref)) {
ret = PTR_ERR(key_ref);
goto error2;
}
keyring = key_ref_to_ptr(keyring_ref);
key = key_ref_to_ptr(key_ref);
if (test_bit(KEY_FLAG_KEEP, &keyring->flags) &&
test_bit(KEY_FLAG_KEEP, &key->flags))
ret = -EPERM;
else
ret = key_unlink(keyring, key);
key_ref_put(key_ref);
error2:
key_ref_put(keyring_ref);
error:
return ret;
}
/*
* Move a link to a key from one keyring to another, displacing any matching
* key from the destination keyring.
*
* The key must grant the caller Link permission and both keyrings must grant
* the caller Write permission. There must also be a link in the from keyring
* to the key. If both keyrings are the same, nothing is done.
*
* If successful, 0 will be returned.
*/
long keyctl_keyring_move(key_serial_t id, key_serial_t from_ringid,
key_serial_t to_ringid, unsigned int flags)
{
key_ref_t key_ref, from_ref, to_ref;
long ret;
if (flags & ~KEYCTL_MOVE_EXCL)
return -EINVAL;
key_ref = lookup_user_key(id, KEY_LOOKUP_CREATE, KEY_NEED_LINK);
if (IS_ERR(key_ref))
return PTR_ERR(key_ref);
from_ref = lookup_user_key(from_ringid, 0, KEY_NEED_WRITE);
if (IS_ERR(from_ref)) {
ret = PTR_ERR(from_ref);
goto error2;
}
to_ref = lookup_user_key(to_ringid, KEY_LOOKUP_CREATE, KEY_NEED_WRITE);
if (IS_ERR(to_ref)) {
ret = PTR_ERR(to_ref);
goto error3;
}
ret = key_move(key_ref_to_ptr(key_ref), key_ref_to_ptr(from_ref),
key_ref_to_ptr(to_ref), flags);
key_ref_put(to_ref);
error3:
key_ref_put(from_ref);
error2:
key_ref_put(key_ref);
return ret;
}
/*
* Return a description of a key to userspace.
*
* The key must grant the caller View permission for this to work.
*
* If there's a buffer, we place up to buflen bytes of data into it formatted
* in the following way:
*
* type;uid;gid;perm;description<NUL>
*
* If successful, we return the amount of description available, irrespective
* of how much we may have copied into the buffer.
*/
long keyctl_describe_key(key_serial_t keyid,
char __user *buffer,
size_t buflen)
{
struct key *key, *instkey;
key_ref_t key_ref;
char *infobuf;
long ret;
int desclen, infolen;
key_ref = lookup_user_key(keyid, KEY_LOOKUP_PARTIAL, KEY_NEED_VIEW);
if (IS_ERR(key_ref)) {
/* viewing a key under construction is permitted if we have the
* authorisation token handy */
if (PTR_ERR(key_ref) == -EACCES) {
instkey = key_get_instantiation_authkey(keyid);
if (!IS_ERR(instkey)) {
key_put(instkey);
key_ref = lookup_user_key(keyid,
KEY_LOOKUP_PARTIAL,
KEY_AUTHTOKEN_OVERRIDE);
if (!IS_ERR(key_ref))
goto okay;
}
}
ret = PTR_ERR(key_ref);
goto error;
}
okay:
key = key_ref_to_ptr(key_ref);
desclen = strlen(key->description);
/* calculate how much information we're going to return */
ret = -ENOMEM;
infobuf = kasprintf(GFP_KERNEL,
"%s;%d;%d;%08x;",
key->type->name,
from_kuid_munged(current_user_ns(), key->uid),
from_kgid_munged(current_user_ns(), key->gid),
key->perm);
if (!infobuf)
goto error2;
infolen = strlen(infobuf);
ret = infolen + desclen + 1;
/* consider returning the data */
if (buffer && buflen >= ret) {
if (copy_to_user(buffer, infobuf, infolen) != 0 ||
copy_to_user(buffer + infolen, key->description,
desclen + 1) != 0)
ret = -EFAULT;
}
kfree(infobuf);
error2:
key_ref_put(key_ref);
error:
return ret;
}
/*
* Search the specified keyring and any keyrings it links to for a matching
* key. Only keyrings that grant the caller Search permission will be searched
* (this includes the starting keyring). Only keys with Search permission can
* be found.
*
* If successful, the found key will be linked to the destination keyring if
* supplied and the key has Link permission, and the found key ID will be
* returned.
*/
long keyctl_keyring_search(key_serial_t ringid,
const char __user *_type,
const char __user *_description,
key_serial_t destringid)
{
struct key_type *ktype;
key_ref_t keyring_ref, key_ref, dest_ref;
char type[32], *description;
long ret;
/* pull the type and description into kernel space */
ret = key_get_type_from_user(type, _type, sizeof(type));
if (ret < 0)
goto error;
description = strndup_user(_description, KEY_MAX_DESC_SIZE);
if (IS_ERR(description)) {
ret = PTR_ERR(description);
goto error;
}
/* get the keyring at which to begin the search */
keyring_ref = lookup_user_key(ringid, 0, KEY_NEED_SEARCH);
if (IS_ERR(keyring_ref)) {
ret = PTR_ERR(keyring_ref);
goto error2;
}
/* get the destination keyring if specified */
dest_ref = NULL;
if (destringid) {
dest_ref = lookup_user_key(destringid, KEY_LOOKUP_CREATE,
KEY_NEED_WRITE);
if (IS_ERR(dest_ref)) {
ret = PTR_ERR(dest_ref);
goto error3;
}
}
/* find the key type */
ktype = key_type_lookup(type);
if (IS_ERR(ktype)) {
ret = PTR_ERR(ktype);
goto error4;
}
/* do the search */
key_ref = keyring_search(keyring_ref, ktype, description, true);
if (IS_ERR(key_ref)) {
ret = PTR_ERR(key_ref);
/* treat lack or presence of a negative key the same */
if (ret == -EAGAIN)
ret = -ENOKEY;
goto error5;
}
/* link the resulting key to the destination keyring if we can */
if (dest_ref) {
ret = key_permission(key_ref, KEY_NEED_LINK);
if (ret < 0)
goto error6;
ret = key_link(key_ref_to_ptr(dest_ref), key_ref_to_ptr(key_ref));
if (ret < 0)
goto error6;
}
ret = key_ref_to_ptr(key_ref)->serial;
error6:
key_ref_put(key_ref);
error5:
key_type_put(ktype);
error4:
key_ref_put(dest_ref);
error3:
key_ref_put(keyring_ref);
error2:
kfree(description);
error:
return ret;
}
/*
* Call the read method
*/
static long __keyctl_read_key(struct key *key, char *buffer, size_t buflen)
{
long ret;
down_read(&key->sem);
ret = key_validate(key);
if (ret == 0)
ret = key->type->read(key, buffer, buflen);
up_read(&key->sem);
return ret;
}
/*
* Read a key's payload.
*
* The key must either grant the caller Read permission, or it must grant the
* caller Search permission when searched for from the process keyrings.
*
* If successful, we place up to buflen bytes of data into the buffer, if one
* is provided, and return the amount of data that is available in the key,
* irrespective of how much we copied into the buffer.
*/
long keyctl_read_key(key_serial_t keyid, char __user *buffer, size_t buflen)
{
struct key *key;
key_ref_t key_ref;
long ret;
char *key_data = NULL;
size_t key_data_len;
/* find the key first */
key_ref = lookup_user_key(keyid, 0, KEY_DEFER_PERM_CHECK);
if (IS_ERR(key_ref)) {
ret = -ENOKEY;
goto out;
}
key = key_ref_to_ptr(key_ref);
ret = key_read_state(key);
if (ret < 0)
goto key_put_out; /* Negatively instantiated */
/* see if we can read it directly */
ret = key_permission(key_ref, KEY_NEED_READ);
if (ret == 0)
goto can_read_key;
if (ret != -EACCES)
goto key_put_out;
/* we can't; see if it's searchable from this process's keyrings
* - we automatically take account of the fact that it may be
* dangling off an instantiation key
*/
if (!is_key_possessed(key_ref)) {
ret = -EACCES;
goto key_put_out;
}
/* the key is probably readable - now try to read it */
can_read_key:
if (!key->type->read) {
ret = -EOPNOTSUPP;
goto key_put_out;
}
if (!buffer || !buflen) {
/* Get the key length from the read method */
ret = __keyctl_read_key(key, NULL, 0);
goto key_put_out;
}
/*
* Read the data with the semaphore held (since we might sleep)
* to protect against the key being updated or revoked.
*
* Allocating a temporary buffer to hold the keys before
* transferring them to user buffer to avoid potential
* deadlock involving page fault and mmap_lock.
*
* key_data_len = (buflen <= PAGE_SIZE)
* ? buflen : actual length of key data
*
* This prevents allocating arbitrary large buffer which can
* be much larger than the actual key length. In the latter case,
* at least 2 passes of this loop is required.
*/
key_data_len = (buflen <= PAGE_SIZE) ? buflen : 0;
for (;;) {
if (key_data_len) {
key_data = kvmalloc(key_data_len, GFP_KERNEL);
if (!key_data) {
ret = -ENOMEM;
goto key_put_out;
}
}
ret = __keyctl_read_key(key, key_data, key_data_len);
/*
* Read methods will just return the required length without
* any copying if the provided length isn't large enough.
*/
if (ret <= 0 || ret > buflen)
break;
/*
* The key may change (unlikely) in between 2 consecutive
* __keyctl_read_key() calls. In this case, we reallocate
* a larger buffer and redo the key read when
* key_data_len < ret <= buflen.
*/
if (ret > key_data_len) {
if (unlikely(key_data))
kvfree_sensitive(key_data, key_data_len);
key_data_len = ret;
continue; /* Allocate buffer */
}
if (copy_to_user(buffer, key_data, ret))
ret = -EFAULT;
break;
}
kvfree_sensitive(key_data, key_data_len);
key_put_out:
key_put(key);
out:
return ret;
}
/*
* Change the ownership of a key
*
* The key must grant the caller Setattr permission for this to work, though
* the key need not be fully instantiated yet. For the UID to be changed, or
* for the GID to be changed to a group the caller is not a member of, the
* caller must have sysadmin capability. If either uid or gid is -1 then that
* attribute is not changed.
*
* If the UID is to be changed, the new user must have sufficient quota to
* accept the key. The quota deduction will be removed from the old user to
* the new user should the attribute be changed.
*
* If successful, 0 will be returned.
*/
long keyctl_chown_key(key_serial_t id, uid_t user, gid_t group)
{
struct key_user *newowner, *zapowner = NULL;
struct key *key;
key_ref_t key_ref;
long ret;
kuid_t uid;
kgid_t gid;
unsigned long flags;
uid = make_kuid(current_user_ns(), user);
gid = make_kgid(current_user_ns(), group);
ret = -EINVAL;
if ((user != (uid_t) -1) && !uid_valid(uid))
goto error;
if ((group != (gid_t) -1) && !gid_valid(gid))
goto error;
ret = 0;
if (user == (uid_t) -1 && group == (gid_t) -1)
goto error;
key_ref = lookup_user_key(id, KEY_LOOKUP_CREATE | KEY_LOOKUP_PARTIAL,
KEY_NEED_SETATTR);
if (IS_ERR(key_ref)) {
ret = PTR_ERR(key_ref);
goto error;
}
key = key_ref_to_ptr(key_ref);
/* make the changes with the locks held to prevent chown/chown races */
ret = -EACCES;
down_write(&key->sem);
{
bool is_privileged_op = false;
/* only the sysadmin can chown a key to some other UID */
if (user != (uid_t) -1 && !uid_eq(key->uid, uid))
is_privileged_op = true;
/* only the sysadmin can set the key's GID to a group other
* than one of those that the current process subscribes to */
if (group != (gid_t) -1 && !gid_eq(gid, key->gid) && !in_group_p(gid))
is_privileged_op = true;
if (is_privileged_op && !capable(CAP_SYS_ADMIN))
goto error_put;
}
/* change the UID */